EVALUATION OF ISOKINETIC MUSCLE STRENGTH MEASUREMENTS IN PATIENTS WITH UNILATERAL DEVELOPMENTAL DYSPLASIA OF THE HIP TREATED WITH ONE-STAGE COMBINED PROCEDURE

Abstract

Aim: Patients treated with one-stage combined operations after walking age for developmental dysplasia of the hip (DDH), and whose follow-up revealed both clinical and radiological complete healing underwent flexor and extensor isokinetic muscle strength (IMS) measurements of the hip and results were evaluated in comparison with the contralateral hips.

Methods: A total of 22 patients with unilateral DDH and treated with one-stage combined operations after walking age were included in the study. All patients were operated by the same surgeon. In their last follow-up visit, all patients were functionally excellent in accordance with the Barrett’s Modified McKay Criteria and according to the Severin’s Classification for radiological grading of the hip all cases were type I. IMS of hip flexors and extensors were tested by Biodex 3 Pro isokinetic test device at 120º/sc and 240º/sc. In all patients, peak torque (PT), peak torque angle (PTA), total work (TW), and average power (AP) values of operated and non-operated hips were measured at both angular velocities and recorded separately for flexors and extensors. For comparative evaluation, values of the operated and non-operated hips were used for determining the differences in IMS (DIMS), total work (DTW), and average power (DAP). In statistical assessment; Student’s t test, paired t test, and Spearman’s Rank correlation analysis were used.

Results: The mean age of patients were 12,8±2,9 (9–18) years old. At the last control visit, the mean value of follow-up periods were 112,6±32,0 (68–159) months. Parameters like age, age at the time of operation, and the length of postoperative follow-up period showed no statistical relation with IMS measurements (p> 0,05). For flexors, TW was lower at the operated hip when compared with the non-operated hip at 120º/sc and 240º/sc (p=0,001 and p=0,002, respectively). AP was lower at the operated hip at 120º/sc and 240º/sc (p=0,011 and p=0,003, respectively). PT was lower at the operated hip (22,5±11,3) when compared with the non-operated hip (27,1±12,1) only at 120º/sc (p=0,001). For extensor muscles, PT, TW, AP, and PTA showed no statistically significant difference (p> 0,05). For flexors, the DIMS between operated and non-operated hips at 120º/sc and 240º/sc were measured as −15,3±22,2% (median;-14,4) and −8,0±21,4% (median;−2,5), respectively.

Conclusions: In operated DDH patients with a mean follow-up period of around 10 years, IMS measurements revealed that the flexor muscle strength of the operated hip was still weaker than the non-operated hip. At 120º/sc, which represented evaluation against higher resistance, DIMS, DWF, and DAP were higher when compared with 240º/sc. This finding shows that hip flexors of these patients may remain weak in activities like sports, which require more resistance.